Various kinds of electromagnetic gaskets have already been proposed which are useful for ensuring the electric continuity of assembled parts and therefore for creating a barrier against electromagnetic radiation.
Thus, there has been proposed gaskets obtained by moulding or extrusion and made of conductive elastomeric materials which form an electromagnetic shield as well as providing an environmental shield when the gasket is interposed between two parts. However, the manufacture of these gaskets is still very costly.
Gaskets are also made from electrically conductive wire mesh which form a gasket of interlocked wires. Such gaskets do not have a satisfactory resiliency, can be crushed easily and take a permanent compression set so that the electromagnetic energy can pass through the gasket.
Electromagnetic shielding gaskets are also formed of a core of an elastomeric material and of a wire sleeve knitted over the core. Consequently the sleeve and the core of the gasket form a loose assembly the control and the handling of which are therefore not easy. Additionally, it requires that the process of core vulcanization and the process of knitting the wire sleeve around this core be done consecutively, which is a long and costly procedure.
Further, it has been known to flatten a knitted mesh, wrap it around a core and clench it along one side of the core rather than knitting the mesh over the core. The retention of the mesh around the core is generally poor and the process requires several consecutive, separate steps; forming and vulcanizing the core, knitting the mesh, flattening the mesh and wrapping it around the core.